Optical Network Unit Registration via Dynamic Wavelength Scanning
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Solution Overview
Problem
In TDM/WDM-PON systems, unregistered optical network units (ONUs) face challenges in efficiently receiving discovery gate messages due to varying dynamic bandwidth allocation periods, leading to prolonged registration sequences as they inefficiently search for coincident wavelengths, especially when the wait time is not appropriately set in response to changes in DBA periods.
Innovation Solution
The method involves periodically transmitting bandwidth allocation signals by OSUs, with ONUs calculating a second period based on reception intervals and changing their transmissive wavelengths at a third period longer than the calculated second period to ensure reliable registration, thereby setting a wait time that satisfies the condition TT-FL > TDIS, allowing for quicker discovery sequence completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unregistered ONU periodically changes transmissive wavelength to search for discovery gate messages, then registration can be completed, but registration time is prolonged due to inefficient wavelength searching
Solution Approach 1:
The ONU monitors the reception interval of bandwidth allocation signals and uses this feedback to dynamically calculate and adjust the wavelength change period. This feedback mechanism allows the ONU to adapt its wavelength searching speed based on actual system conditions, avoiding both premature wavelength changes (which would miss discovery gate messages) and unnecessarily slow searching (which prolongs registration time).
Solution Approach 2:
The patent transforms the static wavelength searching process into a dynamic one by continuously adjusting the wavelength change period based on the calculated second period from bandwidth allocation signal intervals. This dynamic adjustment allows the system to optimize registration speed while maintaining reliability under varying DBA period conditions.
2Loss of time
If wait time is set short to speed up registration, then registration time is reduced, but discovery gate messages may be missed when DBA periods vary
Solution Approach 1:
The patent changes the wait time parameter dynamically based on the calculated second period derived from bandwidth allocation signal reception intervals. By adjusting the wavelength change period to be longer than the calculated second period, the system adapts wait time to actual DBA period conditions, ensuring discovery gate messages are not missed while minimizing registration time.
3Ease of operation
If ONU uses fixed wavelength change interval to search for discovery gate messages, then wavelength searching is simple, but registration efficiency decreases when DBA periods change
Solution Approach 1:
The patent replaces the fixed wavelength change interval with a dynamic calculation based on the second period derived from actual bandwidth allocation signal reception intervals. This dynamic approach maintains operational simplicity through automated calculation while significantly improving registration efficiency by adapting to varying DBA periods.
Solution Approach 2:
The ONU autonomously calculates the appropriate wavelength change period based on its own reception interval measurements of bandwidth allocation signals. This self-service mechanism eliminates the need for external configuration or complex centralized control, maintaining ease of operation while achieving adaptive optimization.
Data Source
AI summary
In a telecommunications network including an optical line terminal (OLT) having optical subscriber units (OSUs) and an optical network unit (ONU) connected to the OLT, bandwidth allocation signals are periodically transmitted at a first period from the respective OSUs to the ONU, and an acknowledgement request signal is transmitted from at least one of the OSUs to the ONU at a second period having a value corresponding to the first period multiplied by a constant. If an ONU is registered in none of the OSUs, the first period is determined from reception intervals of the assignment signals, and a second period is calculated from the first period. Transmissive wavelength of a variable-wavelength (VW) filter in the ONU is periodically changed at a third period longer than the second period. In the OSU having transmitted the request signal, the unregistered ONU having received the request signal is registered.